First check you have not set Finder's preferences to hide file extensions: see how. If you have, you will not see any file extensions!
If a Tinderbox file has no '.tbx' extension, even when extensions are shown, then there are some possible causes:
- If you used Tinderbox before July 2005 (v2.5), the application did not add extensions and relied on old-style Mac OS resource fork info. All such legacy Tinderbox files should now be given a '.tbx' extension.
- You somehow deleted the extension. If you are certain the file is a Tinderbox document, then give it a '.tbx' extension and try opening it
- The file is not really a Tinderbox file. Either—if confident to look at XML—look at the source code in a text editor. A Tinderbox file will mention the app name on line #2 of the code. Or, send a copy of the file to support (firstname.lastname@example.org).
Now your files have the correct extension they should show a Tinderbox file icon and you should be able to open then simply by double-clicking their file icon. If not, see here.